Beater sizing of paper with ketene dimers



United States Patent BEATER SIZING OF PAPER WITH KETENE DIMERS WilfredE. Osberg, Jr., Newport, Del., assignor to Hercules Powder Company,Wilmington, DeL, a corporation of Delaware No Drawing. Application April15, 1954, Serial No. 423,521

8 Claims. (Cl. 92-21) This invention relates to a process of beatersizing paper with higher organic ketene dimers.

In the sizing of paper it is conventional to add a sizing agent, suchas, usually, rosin size, and, occasionally, wax,

asphaltic material, or the like to the pulp slurry before the sheet isformed. These sizing materials are precipitated on the pulp by theaddition of papermakers alum which is added to the pulp slurry to bringthe pH to'4 to 4.5. This is termed the beater sizing process. The bulkof sized paper prepared in this country is beater sized. A much smalleramount of paper is sized by applying a sizing agent to the surface ofthe paper sheet.

Recently, in U. S. Patent 2,627,477 to William Downey, it is disclosedthat ketene dimer emulsions are useful in the surface sizing of paper.The emulsions are not substantive to the cellulose fibers so thatheretofore it has not been practical to use these emulsions in beatersizing.

There has now been discovered apracticable process whereby aqueousemulsions of ketene dimers, as described in the said patent to Downey,may be used in a heater sizing process. In this process ketene dimeremulsions are added to the beater at a concentration of from about partsof ketene dimer per million parts of water to about 200 parts of ketenedimer per million parts of 7 water, and the pH of the pulp slurry isadjusted to within the range of 5 to 9, inclusive. The pulp is thenformed into a sheet and dried. If desired, the sheet may be cured byheating to a relatively elevated temperature, say about 100 C., for ashort period of time such as about 10 minutes. However, this is notnecessary as adequate sizing develops on mere standing at roomtemperature for a few hours. Furthermore, if the sheet is prepared at arelatively high pH, such as about 8.5 or higher, a sheet will be sizedas it comes oif the machine so that additional curing is not needed.

This process has several advantages. Thus, it has been found that eventhough the emulsions are not naturally substantive to cellulose they areretained by the cellulose fibers in much greater amounts than theirconcentration in the water would indicate. Further, at the lowconcentrations used in the process of the instant invention, the amountslost in the discarded white water are very small. While the ketene dimeremulsions can be used at the pHs normally used in paper manufacture, ithas been found that the use of the critical pH range reduces almost inhalf the amount of ketene dimer needed to obtain a given degree ofsizing.

The aqueous emulsions when used in this process are stable over theentire pH range of the process and are even stable when subjected to thevigorous mechanical action found in the beater. The discovery that theketene dimer emulsions are stable under these extreme conditions istruly unusual and surprising. Further, the process of the instantinvention obviates the necessity of using alum to fix the size on thepaper fibers. The aqueous emulsions of ketene dimers do not cause foamin the papermaking system, thereby permitting faster machine speeds inthose systems where foam is the limiting factor. The process of theinstant invention, in permitting the 2,785,067 Patented Mar. 12, 1957use of slightly acid and alkaline pHs in the paper system, gives greatlyimproved initial strength to the sheet as well as improved permanence.

The ketene dimers which are used in the instant process are dimershaving the formula ERCH=C=O12 where R is a hydrocarbon radical, such asalkyl having at least 8 carbon atoms, cycloalkyl having at least 6carbon atoms, aryl, aralkyl, and alkaryl. In naming ketene dimers, theradical R is named followed by ketene dimer. Thus, phenyl ketene dimeris:

benzyl ketene dimer is:

and decyl ketene dimer is: [C1oH21-CH=C=O]2. Representative ketenedimers whose emulsions may be used in the process of the instantinvention include octyl, decyl, dodecyl, tetradecyl, hexadecyl,octadecyl, eicosyl, docosyl, tetracosyl, phenyl, benzyl B-naphthyl andcyclohexyl ketene dimers, as well as the ketene dimers prepared frommontanic acid, naphthenic acid, A decylenic acid, n -dodecylenic acid,palmitoleic acid, oleic acid, ricinoleic acid, petroselinic acid,vaccenic acid, linoleic acid, linolenic acid, eleostearic acid, licanicacid, parinaric acid, tariric acid, gadoleic acid, arachidonic acid,cetoleic acid, erucic acid and selacholeic acid, as well as ketenedimers prepared from naturally occurring mixtures of fatty acids, suchas those mixtures found in coconut oil, babassu oil, palrn kernel oil,palm oil, olive oil, peanut oil, rape oil, beef tallow, lard (leaf) andWhale blubber. Mixtures of any of the above-named fatty acids with eachother may also be used. Thus, a mixture of stearic and oleic acids givesa ketene dimer which is very easily emulsified. A mixture which isparticularly preferred is the mixed tetradecy1-, hexadecyl ketene dimerprepared from a mixture of stearic acid and palmitic acid, particularlya mixture of these two acids in approximately equal proportions. Theemulsions used in this process are prepared as set forth in the saidpatent to William Downey.

When there is 0.1% hexadecyl ketene dimerin the paper, based on the dryweight of the paper, only one hydroxyl group in about every ninethousand-present in the cellulose is reacted with the ketene dimer. Nomethod is known by which such minuscule amounts of ketene dimer can bedetermined quantitatively in the presence of such a large amount ofcellulose. Accordingly, the amount of ketene dimer on the paper 'wasdetermined mathematically in Examples 1-11. This method is as follows:The conditions of preparation are kept constant. Thus, a Noble and Woodhandsheet machine is used; A given amount of water was added to thedeckle box and to this was added a given amount of ketene dimeremulsion. Wet 2:1 water to pulp sheets were added to the deckle box andthe squeezings from the squeeze'rolls were caught and poured back to thedeckle box to keep the amount of water constant. The percent of theketene dimer present in the water which is abstracted by the.

. that the diluted paper pulp is treated with X grams or ketene dimer,and assume further that the amount of ketene dimer retained on eachsheet formed is Y% of that present in the water, then the first sheetprepared will contain X times Y grams of ketene dimer, the second sheetwill contain (X-XY)Y grams of ketene dimer,

Knowing the concentration of dimer in the solution, the amount on thesheet was easily calculated.

Table III Percent of Dimer in Paper Sizing Obtained Based on Dry Weightof Paper Ketene Dimer Example Poor, splotchy. No sizing. Poor sizing.

Fair sizing.

Excellent.

Very good. Do. Do.

Excellent.

. Good.

. Fair. 0. 051 Excellent.

-do Ketene dimer prepared from montanic acid. Ketene dimer prepared frommontanic acid.

The above data clearly show that for maximum efiectiveness in sizingwith an alkyl ketene dimer, only octyl and higher alkyl ketene dimersshould be used. The data also clearly show that aralkyl and aryl ketenedimers are effective in sizing paper.

EXAMPLE 29 A ketene dimer emulsion was prepared by blending 100 parts of85% active hexadecyl ketene dimer with parts of xylene, 20 parts ofmethyl oleate and 20 parts of polyoxyethylene sorbitol laurate sold bythe Atlas Powder Company under the trade name Atlox 1045. This mixturewas then melted at 70 C. and water (also at 70 C.) added thereto slowlywhile the mixture was stirred. This formed a water-in-oil emulsion whichat about 50% total solids inverted to give an oil-in-water emulsion.Addition of water was continued until the solids were about 40%whereupon the emulsion was dumped into hot water to give an emulsionhaving about 1.5% solids.

Six beaters were furnished with 2200 lb. each of unbleached kraft pulpat 7% consistency. The pulp was beaten and 2.7 lb. of ketene dimersolids added to each beater together with additional water to give apulp slurry of 4% consistency. There was thus present in the water0.005% ketene dimer based on the water. A closed system was used and asmall additional amount of the ketene dimer emulsion was added to thewhite water so that the concentration of ketene dimer at the wire wasmaintained at about 0.005% ketene dimer based on the water. The pulp wasdiluted with the treated white water and run out on a Fourdrinier papermachine in the usual manner. The pH of the white water was varied byadding caustic. Substantial quantities of paper were made with the pH ofthe white water at 6.7-7.0, 8.5, and 9.6.

The reels were stored overnight at room temperature. The paper preparedat approximately neutral pHs was not appreciably sized as it came offthe machine, while that paper prepared at pHs or" 8.5 and 9.6 was sizedas it came off the machine. Within about two hours of storage at roomtemperature, sizing developed in all sheets, and by the morning afterthe run, all sheets were similarly hard-sized. Although agitation wasquite vigorous in all of the machine chests, the amount of foam in thepulp was negligible. There was also a negligible amount of foam on thewire although the machine was run at 570 ft./min. The paper had a basisweight of lb. per ream and was Yankee dried. It was well sized and onspecification in every respect.

6 EXAMPLE so In another run a 50-lb. unbleached kraft sheet was made ona Fourdrinier machine. The hexadecyl ketene dimer emulsion was preparedas in Example 29. In contrast to Example 29, the emulsion was addedcontinuously to the stock just before the fan pump, additions being madewith both 5 and 7 lb. of the dimer per ton of airdried stock. The pH ofthe system throughout the run was about 8.4. The concentration of ketenedimer at the wire was about 10 parts per million parts of water for theone run and about 14 parts of ketene dimer per million parts of water inthe other run. As compared to similar runs using rosin and alum, therewas a marked reduction in foaming tendency during the period the dimeremulsion was used on the machine, but no other differences in machineoperation were noted.

The ultimate sizing was developed on the machine,no appreciable increasein sizing being noted in subsequent curing. The sizing of paper preparedwith the ketene dimer emulsion was compared with runs made on the samemachine using rosin and alum size. Sizing was determined by noting thetime for penetration of the sized sheet by a 20% aqueous solution oflactic acid. The paper sized with 5 lb. of hexadecyl ketene dimer perton of pulp had a sizing of 893 seconds, while the paper containing 7lb. of hexadecyl ketene dimer per ton of pulp had a sizing of over 2700seconds. In comparison six runs of the standard rosin-sized papercontaining 1% rosin size prepared on this machine had the followingsizing: 333 seconds, 314 seconds, 178 seconds, 355 seconds, 300 seconds,and 393 seconds.

In the above examples definite curing cycles were used to most clearlypoint up the differences due to the controlled variables in theexamples, such as type of ketene, type of pulp, and the pH of the pulpslurry. In commercial practice this is not necessary as can be seen fromExamples 29 and 30. When the paper is dried on a heated roll, or bysimilar means, the heat of drying will generally be suficient to curethe sheet. When an alternative method of drying, such as air drying, isused, simple storage of the paper at room temperature for a day or twowill be sufiicient to cure the sheet. However, a separate curing stepmay be used if desired. When a separate curing step is used, the paperwill generally be heated at about 100 C. for five or ten minutes orlonger.

In the process of beater sizing as the term is used in the art and inthe instant application, it is understood that the ketene dimer may beadded to the paper system at that point which is most convenient to theactual manufacturing needs, such as, for example, by addition of thedimer emulsion to the paper furnish at any point prior to sheetformation, sucl as addition at the head box, fan pump, beater engine,Jordan, or the like. Addition at any point prior to sheet formation isincluded in the term beater addition as used in the art. Furthermore,the ketene dimer emulsions used in the process of the instant inventionmay be used in conjunction with conventional papermaking ingredients,such as, for example, wet strength resins, fillers, dyes, pigments, andthe like, to provide in all cases a paper product having the desiredsizing properties.

As stated before, any of the emulsions of U. S. 2,627,- 477 to WilliamDowney may be used. However, particularly preferred are those emulsionswhich are prepared using a nonionic emulsifier. In addition to thosenonionic emulsifiers specifically used by Downey, those nonionicemulsifiers which have been found to be particularly useful includepolyoxyethylcne sorbitan trioleate, sold by the Atlas Powder Companyunder the trade name Tween polyoxyethylene sorbitol hexaoleate, sold bythe Atlas Powder Company under the trade name Atlox 1086;polyoxyethylene sorbitol laurate, sold by the Atlas Powder Company underthe trade name Atlox 1045; polyoxyethylene sorbitol oleate-laurate, soldby the Atlas Powder Company under the trade name Atlox 1045A;

polyethylene glycol esterfof ro'siffifsold by the Hercules *Powder:Company undef' the 't-rade name Synth'etics V All-1 50 th -pe1 erg 1 neglyeo1 'esfer-ofaosin, sold by the"Hercules Powder Company -'under'-'thenane-"name fSynfhetics AR'ZOO; the polyethylene glycol ether of analkylatedphenol, sold by the Hercules Po'wder'Company under the tradename synthetics AF 100; and finally, the ethylene oxide adduct ofamixture of rosin'and alkylate'cl phenoL-sold by :the Hercules PowderCompany under the trade name synthetics B97? Of the anionic emulsifiers,those whichiare particularly preferred are the alkar'ylsulfonates suchasthat soldby Nino' Laboratories, lnciu'nder the *trade name *Toximul-10G, and the sodium salts of=higher-fatty alcohols, such-as those 's'oldby'E; *I. 'du'Pont de Nemours and Company, Inc.

under the tradefnarne Aquarex D V 'Irclairnr :1. A process for theinternal sizing of paper with a sizing material 'which does not requirethe use of aprecipitating :agent which'comprises adding to an aqueoussuspension of cellulosic paper stock at a point-"ahead of sheetformation =an aqueous emulsion of a keteu'e fdimer, said ketene "dimerhaving --the--' forn'1ula [RCH=C=G]2 where R is a hydrocarbon radicalselected from the group' consisting of-alkyl groups having ;atleast-8carbon atoms, cycloalkyl having at least 6 carbon atoms, aryl,

' aralkyhiandalkaryl groups, said aqueous suspension being ata 'pH of 5m9, inclusive, said ketene dimer being added'to the said aqueoussuspension to give a conce'n 7. "The process'according' to claim 4whereinthejalkyl radical isa mixture of hexadecyl and tetradecyl.

8. The process according to claim 4 wherein theketene' dimer is preparedfrommontanic acid.

ReferencesvCited in the file or this patent UNITED STATES PATENTS1,996,707 Nathansohm Apr.2, 1935 2,285,490 Broderick June 9, 1942'2,595,935 Daniel et al. V May 6, 1952 2,601,597 Daniel et al. June 24,1952 TDOWHCY" Feb. 3,

O H R- REFERENCES Dohne et 9.1.; Pape r Tra'de J. Nov. 27', 1-941,138-144.

1. A PROCESS FOR THE INTERNAL SIZING OF PAPER WITH A SIZING MATERIALKWHICH DOES NOT REQUIRE THE USE OF A PRECIPITATION AGENT WHICH COMPRISESADING TO AN AQUEOUS SUSPENSION OF CELLULOSIC PAPER STOCK AT A POINTAHEAD OF SHEET FORMATION AN AQUEOUS EMULSION OF A KETENE DIMER, SAIDKETENE DIMER HAVING THE FORMULA (RCH=C=O)2 WHERE R IS A HYDROCARBONRADICAL SELECTED FROM THE GROUP CONSISTING OF ALKYL GROUPS HAVING ATLEAST 8 CARBON ATOMS, CYCLOALKYL HAVING AT LEAST 6 CARBON ATOMS, ARYL,ARALKYL, AND ALKARYL GROUPS, SAID AQUEOUS SUSPENSION BEING AT A PH OF 5TO 9, INCLUSIVE, SAID KETENE DIMER BEING ADDED TO THE SAID AQUEOUSSUSPENSION TO GIVE A CONCENTRATION OF FROM ABOUT 5 PARTS OF SAID KETENEDIMER TO ABOUT 200 PARTS OF SAID KETENE DIMER PER MILLION PARTS OFWATER, FORMING A SHEET FROM THE SAID STOCK AND DRYING THE SAID SHEET.